So, Ash-Greninja is not a synchro evolution sort of thing but an alternate forme that is triggered when a Greninja with the ability Battle Bond KO's an enemy pokemon.

Do you think other pokemon will get these abilities? If so, which ones do you think are most likely to get one?

Also, isn't it a bit weird that they opted to go for a special ability instead of making use of the newly introduced Z-Moves? I'm not particulary a fan of the idea of pokemon having z-formes or that kind of stuff, but I think it would have made more sense to give it a special Z-Move that changed its forme.